Oil fuse



J1me 1935- A. G. STEINMAYER El AL 2,003,616

OIL FUSE 2 Sheets-Shget 1 Filed Jan. 25, 1952 3m entor6 (Ittorneg Juhe 4, 1955.

A. G. STEINMAYER ET AL OIL FUSE Filed Jan; 25, 1932 2 Sheets-Sheet 2 attorney Patented June 4, 1935 UNITED STATES OIL FUSE Alwin G. Steinmayer, Milwaukee, and William 0. Schultz, South Milwaukee, Wis., assignors to Line Material Company,

South Milwaukee,

Wis., a corporation of Delaware Application January 25, 1932, Serial No. 588,606

3Claims.

This invention relates to oil fuses, and is particiuarly directed to a fuse link. This invention is acontinuation in part of our priorapplication Serial Number 464,220, filed June 27, 1930, for

5 011 fuses.

Our prior application, noted above, disclosed a plunger or block of insulating material, housed in an oil containing casing and operated by mechanism to open and close a circuit. Stationary contacts were carried within the casing and the plunger carried what may be termed the movablecontacts which contact with and move away from the stationary contacts as the plung- 3' is reciprocated towards open or closed posi- This invention is directed to a fuse link which, in the form shown, is used to join the contacts carried by the plunger, but in its broader aspects is directed particularly to a fuse link irrespective of the particular device with which it is used.

Objects of this invention are to provide a fuse link, eminently suitable in oil fuse work although suitable for other uses, which has a double'reduced section, in which the reduced 7 sections are so located and positioned that very little heat conduction to other portions of the apparatus and very little cooling due to oil circulation can occur, thereby making the calibration more exact or, in other words, more definitely predetermining the load at which the fuse will blow.

A further object is to provide a fuse link in which the central portion drops down upon fus-- ing at the reduced sections thereby producing a 7 long gap in addition .to that produced by the actual fusing.

l 'urtherobjects are'to provide a fuse linkin which wrapped or insulated portions are provided to both reduce conduction of heat and provide additional insulation between the fuse link and the casingor other portions of the device so that even if the fuse is distorted at fusing, undesirable contact cannot occur, and to organize or construct the fuse link with its wrapped portions so that the wrapping or insulating covering of the fuse link offers no hindrance to-the'free dropping away of the intermediate portion when'the fuse link fuses at the spaced reduced portions. 7

Further objects are to provide such a con-. struction that any suitable conducting material such as low melting point alloys, aluminum, or any metal, even copper, may be employed for the fuse link, and to so' construct the wrapped portions that they are separated adjacent the spaced reduced sections to permit free bending of the fuse link and also to facilitate its operation or'functioning at fusing.

Embodiments of the invention are shown in the accompanying drawings, in which:-

Figure lis a side elevation of the oil fuse with portions thereof broken away.

Figure2 is a view of the movable member and associated portions showing the fuse link in place, such view having portions broken away.

Figure 3 is an enlarged fragmentary sectional view on the line 33 of Figure 2.

Figure 4 is a view of one form of the fuse link laid out flat.

Figure 5 is a view of a further form of the fuse link laid out flat with a portion of the insulating sheath broken away. Y

Referring to the drawings, it will be seen that the oil fuse comprises a casing i provided with a hinged cover 2 adapted to be locked in place and equipped with downwardly extending pipelike portions 3, one of which is shown in Figure 1, through which the conductors may extend to the stationary contacts 4 mounted within the casing I. Vents 5 are provided for the casing and attaching or supporting lugs i integrally formed with the casing, all as described in detail in ourabove noted copending application.

The casing is preferably lined with an insulating sheath 1 and is filled with oil and houses areciprocatory member or plunger 8, which is formed of any suitable insulating material, such, for instance, as porcelain. This plunger l, as shown most clearly in Figures 1 and 2, carries the movable contacts 9 which may be formed of laminated material and secured to the metallic blocks or terminals Ill rigidly carried by' the movable member 8. These metallic blocks I. extend on opposite sides of the movable member l, as shown in Figures 2 and 3, and are provided with lugs Ii which receive the fuse strip attaching screws l2.

The movable member 8 is provided with a reduced downwardly extending portion II which has outwardly projecting barriers l4 symmetrically located, as shown in Figures 2 and 3. This entire structure of the movable member may be integral and may, as stated above, be formed of porcelain or other suitable insulating material.

The movable member is raised or lowered by suitable mechanism to thereby cause the movable contacts to engage or disengage the stationary contacts, the movement being imparted to the reciprocatory or movable member 3 through the medium of a transversely extending pin ii located adjacent the upper portion of such member, as shown in Figure 2, and as described in greater detail in our above noted copending application. I

The removable fuse link is held in contact with each of the lugs H by means of the screws or similar fasteners 12, and loops downwardly around the bottom of the movable member or, specifically stated, passes around the bottom of the extension l3, see Figure 3.

The removable fuse link comprises forked end l6 adapted to straddle the threaded stems ll of the screws or fasteners H, see Figure 2. The fuse is provided with two spaced portions l9 and an intermediate portion 20. The portions l9 and 20 are joined by reduced sections 2|.

It is to be noted from Figures 2 and 3 that the reduced sections are located adjacent the lower corners of the portion l3 of the movable member and contact with such movable member in the form of fuse link shown in Figures 2,3 and 4, only at such corner portion. These reduced sections facilitate the folding of the fuse link or bending at these points, and the slight arching of the fuse link holds it out of contact with any but the corner portion of the member l3, as shown most clearly in Figure 3. Thus there is very little'heat conduction to the member 13.

The reduced sections are fused when an overload occurs and the intermediate section drops downwardly away from the bottom of the portion I3 and thus widens the gap in addition to that produced by the fusing of the link.

The fuse'link is wrapped with paper, fiber, or 'other'insulating material, and in the form shown in Figure 4, three wrapped sections are provided, as indicated at 22, for the portions I9 and at 23 for the portion 20. r.

In the form shown in Figure the wrapping or covering extends from adjacent one end of the fuse to adjacent the other end of the fuse. However, this insulating sheath is separated into three-sections by the slits 26, as shown in Figure 5. The sections 24 cover the portions 19, and the section 25 covers the portion 20, the ends of such section abutting.

This construction permits ready folding of the fuse at the reduced portions 2| which come-- spondto the position of the slits 26, as may be seen from Figure 5, and when the fuse blows, permits the intermediate section to drop downwardly in a free and unobstructed manner in the same way as in the form previously described.

While it has been stated that the portions are wrapped with the insulating material, nevertheless they may be covered in any suitable manner.

The construction of fuse link prevents rapid cooling of the fuse either by conduction to the other portions of the apparatus or by the free circulation of oil. The oil cannot readily cool the major portion of the fuse link as thisportion is housed, and in addition, only a small portion of the fuse link is exposed to the oil adjacent the reduced sections in the form shown in Figures 2, 3 and 4. a

When the fuse link of. the'fo'rm shown. in Figure 5 is used, the same results are produced, but in addition, there is even less free circulation of oil at the reduced sections and consequently there is even less chance for the oil to cool the fuse at its reduced sections.

Another desirable feature is that in the event a severe overload occurs and the fuse becomes distortedv at the time it fuses, nevertheless inadvertent contact of the remaining portions of the fuse link with other parts of the apparatus is prevented by the insulating sheath or wrappin Further than this, by preventing the rapid cooling of the fuse link, it has been found that the value of current at which the fuse blows, or, in other words, the rating of the fuse, may be very accurately predetermined and thus one of the variables in fuse work is materially reduced, so that a high degree of precision for the rating of the fuse is easily secured.

While it is apparent that various insulating materials canbe employed for the covering of the three sections of the fuse, nevertheless it has been found that where insulating coverings are employed which have a poor thermal conductivity, such as those previously described or allied types of materials, that the cooling of the fuse link by the oil is avoided with greater certainty than where high heat conductivity coverings are employed. The consequence of this is that where coverings of poor thermal conductivity, as'those described, are employed, that the accuracy of the fuse is increased, as has been previously described.

It will be seen further that the construction is relatively simple and iseasy to produce. It also is inexpensive and lends itself readily: to quantity production. I

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative.

rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed. I

We claim: a '1. An oil fuse comprising a casing adapted to contain oil, a blockpositioned within said casing and projecting downwardly thereof and spaced from the bottom of said casing, and a fuse link extending from opposite sides of said block around the bottom of said block, said fuse link having a reduced portion adjacent each side of said block, whereby when said fuse blows the bottom portion thereof between said reduced portion will drop downwardly from said block, said fuse link having the reduced portions bare and having other portions thereof covered with insulating material .of poor thermal conductivity. 2. In an oil fuse, the combination of a casing adapted to contain oil, an insulating member projecting downwardly into said casing, a fuse link carried by said insulatingmember and .projecting downwardly into said oil, said fuse link being looped around the lower portion of said insulating member and having intermediate reduced portions, said fuse link being bent at said intermediate reduced portions, and an insulat ing sheath of poor thermal conductivity covering said fuse link and'having separate portions arranged in substantially abutting relation at the reduced portions of said fuse-link, whereby cooling of said fuse link by the said oil is re duced. a j V 3. A fuse link comprising an elongated conducting member having end portions and an intermediate portion and having reducedpo'r tions joining said end and intermediate portions, said fuse link being covered by sheaths formed of insulating material of poor thermal conductivity, said sheaths consisting of a central sheath and two end sheaths, said central sheath having its edges abutting the adjacent edges of the end sheaths, and said abutting edges being located at said reduced portions.

ALWIN G. STEINMAYER.

WILLIAM O. SCHULTZ. 

